JP2015205295A - Bottom electrode of resistance welder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bottom electrode of a resistance welder by which attachment and detachment of a guide pin can be certainly performed with one touch.SOLUTION: A bottom electrode of a resistance welder in which an electrode tip 2, which is provided with a pore 2a for insertion of a guide pin 4, is attached to a tip of a cylindrical electrode holder 1, while a rod 3 capable of freely and vertically moving, to a tip of which the guide pin 4 is attached, is disposed in the electrode holder 1, and by vertical movement of this rod 3, the tip of the guide pin 4 can freely go in and out from the pore 2a of the electrode tip 2. The tip of the rod 3 is provided with a reception part 6 for a lower end part of the guide pin 4, a ball-type chuck mechanism 7 is attached to the reception part 6, and a ball 8 of the chuck mechanism goes in and out an annular groove part 4b formed in the lower end part of the guide pin 4, whereby the guide pin 4 can be attached and detached.

Description

  The present invention relates to a lower electrode of a resistance welder capable of reliably attaching and detaching guide pins with one touch.

  Conventionally, in an automobile assembly process or the like, a projection nut is welded onto a steel plate as a workpiece using a resistance welding machine. In such a resistance welding machine, the workpiece and the projection nut are set between the upper and lower electrodes, and the welding process is performed by applying a current under pressure. On the other hand, since it is necessary to accurately position the workpiece and the projection nut, a guide pin is attached to the lower electrode, and the guide pin is inserted into the hole portion of the workpiece and the nut to position both of them. (For example, refer to Patent Documents 1 to 3).

  Usually, the guide pin is made of ceramic having excellent heat resistance, but since it is used under high temperature and high pressure, it will be worn or damaged when used for a long time. For this reason, it has been necessary to periodically replace the guide pins in a relatively short time. However, the guide pin is usually screwed to the tip of a rod that moves up and down in the cylindrical electrode holder. Therefore, the guide pin replacement operation is complicated and takes a long time.

  As a result, there is a problem that the work efficiency is lowered due to the replacement of the guide pins. Particularly, when the robot arm of the automobile assembly process is used, the efficiency of the guide pin replacement work is reduced. In order to reduce efficiency, there has been a demand for the development of a new technology that can be attached and detached with one touch.

JP-A-6-246460 Japanese Patent Laid-Open No. 10-328852 JP 2009-255151 A

  The present invention solves the above-described problems, and the guide pin can be attached and detached reliably with one touch. In addition, the guide pin can be exchanged smoothly in the robot arm. An object of the present invention is to provide a lower electrode of a resistance welder that can remarkably improve the overall working efficiency of an assembly process and the like.

The lower electrode of the resistance welding machine of the present invention made to solve the above problems is
At the tip of the cylindrical electrode holder, attach an electrode tip with a hole for inserting the guide pin,
On the other hand, a rod that can be moved up and down with a guide pin attached to the tip is placed in the electrode holder,
A lower electrode of a resistance welding machine in which the tip of the guide pin can be protruded and retracted from the hole of the electrode tip by moving the rod up and down,
A guide pin lower end receiving portion is provided at the tip of the rod, and a ball chuck mechanism is attached to the receiving portion.
The guide pin is attached and detached by causing the ball of the chuck mechanism to appear and disappear in an annular groove formed at the lower end of the guide pin.

The ball chuck mechanism is
A ball slidably set in a ball holding hole formed in a radial direction on the peripheral wall surface of the receiving portion;
It is a cylinder that covers the peripheral wall surface and is freely slidable up and down, and is normally repelled on the front side of the electrode by a resilient member,
A tapered surface having an inner diameter gradually increasing toward the upper end opening is formed on the inner peripheral surface of the cylindrical body,
When the cylindrical body is positioned on the front side of the electrode, the portion with the small inner diameter of the tapered surface presses the ball toward the center portion, so that the ball tip engages with the annular groove provided at the lower end of the guide pin. When,
When the cylindrical body is moved to the rear side of the electrode against the impact, the ball is retracted until it comes into contact with a portion having a large inner diameter of the tapered surface, and the ball tip portion is disengaged from the annular groove portion. What has the structure which can take an aspect is preferable, and let this be the invention which concerns on Claim 2.

  A plurality of the ball holding holes are preferably formed at equal intervals in the radial direction of the peripheral wall surface.

  In the invention according to claim 1, an electrode tip provided with a hole for inserting a guide pin is attached to the tip of a cylindrical electrode holder, while the electrode holder is provided with a guide pin at the tip thereof. A lower electrode of a resistance welding machine in which the tip of the guide pin can be protruded and retracted from the hole of the electrode tip by moving the rod up and down, and the receiving portion of the lower end of the guide pin at the tip of the rod In addition, a ball chuck mechanism is attached to the receiving portion, and the guide pin is attached and detached by causing the ball of the chuck mechanism to protrude and retract in an annular groove formed in the lower end portion of the guide pin. By operating the chuck type mechanism, the guide pin can be easily attached and detached with one touch.

  In the invention according to claim 2, the ball chuck mechanism includes a ball set slidably in a ball holding hole formed in a radial direction on the peripheral wall surface of the receiving portion, and slides up and down covering the peripheral wall surface. It consists of a cylindrical body that is free and is always resiliently projected by a resilient member toward the front side of the electrode, and a tapered surface whose inner diameter gradually increases toward the upper end opening is formed on the inner peripheral surface of this cylindrical body. When the cylindrical body is located on the front side of the electrode, a portion with a small inner diameter of the tapered surface presses the ball toward the center portion, whereby the tip of the ball is engaged with the annular groove provided at the lower end of the guide pin. When the cylindrical body is moved to the rear side of the electrode against the impact, the ball retreats until it comes into contact with the portion having the large inner diameter of the tapered surface, and the ball tip engages with the annular groove. To take two forms of solving Since a wear configuration, only the operation to move the cylindrical body to elastically in contrast with the electrode rear side and can be performed reliably removable guide pins.

  Further, in the invention according to claim 3, since the plurality of ball holding holes are formed at equal intervals in the radial direction of the peripheral wall surface, the guide pins can be firmly fixed by engaging the plurality of balls with the annular groove portion. It becomes possible to hold.

It is a front longitudinal cross-sectional view which shows the whole lower electrode of this invention. It is explanatory drawing which shows the action | operation of a chuck mechanism. It is a front view which shows a guide pin. FIG. 3 is a cross-sectional explanatory view taken along line AA of FIG. 2 showing a state in which the ball has advanced. FIG. 3 is a cross-sectional explanatory view taken along the line AA of FIG. 2 showing a state in which the ball is retracted.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a front longitudinal sectional view showing the entire lower electrode in the resistance welder of the present invention. In the figure, 1 is a cylindrical electrode holder, 2 is an electrode tip attached to the tip, and a rod 3 that can be raised and lowered is arranged in the electrode holder 1. A guide pin 4 is attached to the tip of the rod 3, and an air supply port 5a and a discharge port 5b for moving the rod 3 up and down are attached to the rear end side. The above configuration is basically the same as the conventional lower electrode of this type.

FIG. 2 is an explanatory view showing the operation of the chuck mechanism, the left half is a cutaway sectional view showing a normal state, the right half is a cutaway sectional view showing a state in which the cylinder is pushed down, and FIG. It is a front view which shows a pin.
As shown in the figure, a cylindrical receiving portion 6 into which the lower end shaft portion 4a of the guide pin 4 can be inserted is provided at the tip of the rod 3, and a ball chuck mechanism 7 is attached to the receiving portion 6. It has been. The guide pin 4 is configured to be attached and detached by causing the ball of the chuck mechanism 7 to protrude and retract in an annular groove 4b formed in the lower end shaft portion 4a of the guide pin 4.

Here, the ball chuck mechanism 7 will be described.
The ball chuck mechanism 7 includes a ball 8 slidably set in a ball holding hole 6b formed in a radial direction on the peripheral wall surface 6a of the receiving portion 6, and slidable up and down covering the peripheral wall surface 6a. In addition, it is composed of a cylindrical body 9 that is normally bulleted on the front side of the electrode (see FIGS. 4 to 5). Reference numeral 10 denotes a resilient member such as a coil spring, which is interposed between the lower end of the tubular body 9 and the step portion 11 provided on the rod 3, and is configured to always repel the tubular body 9 toward the front side of the electrode. (See the left half of Figure 2).

A tapered surface 9 a having an inner diameter gradually increasing toward the upper end opening is formed on the inner peripheral surface of the cylindrical body 9, and the guide pin 4 is attached and detached depending on the contact state between the tapered surface 9 a and the ball 8. It is configured.
In other words, when the cylindrical body 9 is positioned on the front side of the electrode, a portion having a small inner diameter of the tapered surface 9a presses the ball 8 toward the center portion, so that the ball tip portion is provided at the lower end portion of the guide pin 4. The guide pin 4 is firmly fixed to the tip of the rod 3 by engaging with the groove 4b (see the left half of FIG. 2). On the other hand, when the cylindrical body 9 is moved to the rear side of the electrode against the impact, the ball 8 retreats until it comes into contact with a portion having a large inner diameter of the tapered surface 9a, and the ball tip portion is engaged with the annular groove portion 4b. As a result, the guide pin 4 can be easily detached from the tip of the rod 3 (see the right half of FIG. 2).

  In the illustrated example, three ball holding holes 6b are formed at equal intervals in the radial direction of the peripheral wall surface 6a. By locking the annular groove 4b at the lower end of the guide pin 4 with a plurality of ball tip portions, the guide pin 4 can be held firmly. There is no problem if the number of the ball holding holes 6b is two or more.

Next, attachment / detachment of the guide pin in the lower electrode configured as described above will be described.
In the normal state, as shown in the left half of FIG. 2, the cylindrical body 9 is in a state of being bulleted by the bullet member 10 and pushed up to the front side of the electrode. At this time, the ball 8 is pushed by a portion having a small inner diameter located at a lower portion of the tapered surface 9a and moves toward the center. As a result, as shown in FIG. 4, the tip of the ball protrudes inward from the peripheral wall surface 6a, and this protruding portion engages with the annular groove 4b provided at the lower end of the guide pin 4 to firmly fix the guide pin 4. Will be.

  On the other hand, as shown in the right half of FIG. 2, when the cylindrical body 9 is pushed down against the electrode against the elastic force of the elastic member 10, the ball 8 has an inner diameter located above the tapered surface 9a. It is possible to retreat until it touches the large part of the. As a result, as shown in FIG. 5, the ball tip is retracted until it does not protrude inward from the peripheral wall surface 6a, the engagement of the guide pin 4 with the annular groove 4b is released, and the guide pin 4 is received by the receiving portion. 6 can be easily removed.

  As is clear from the above description, the present invention provides a receiving portion for the lower end portion of the guide pin at the tip of the rod, and a ball chuck mechanism is attached to the receiving portion, and the ball of the chuck mechanism is attached to the lower end portion of the guide pin. Since the guide pin is attached and detached by making it appear and disappear in the formed annular groove, the guide pin can be attached and detached easily and reliably by operating the ball chuck mechanism. As a result, even when used for a robot arm in an automobile assembly process, for example, there is an advantage that guide pin replacement work can be performed quickly and work efficiency of the entire assembly process can be improved. Further, it has a simple structure and has an advantage that it can be applied to all types of lower electrodes and an advantage that it can be manufactured at low cost.

DESCRIPTION OF SYMBOLS 1 Electrode holder 2 Electrode tip 2a Guide pin insertion hole 3 Rod 4 Guide pin 4a Lower end shaft 4b Annular groove 5a Supply port 5b Discharge port 6 Receiving portion 6a Peripheral wall surface 6b Ball holding hole 7 Ball chuck mechanism 8 Ball 9 Cylindrical body 9a Tapered surface 10 Elastic member 11 Step

Claims (3)

At the tip of the cylindrical electrode holder, attach an electrode tip with a hole for inserting the guide pin,
On the other hand, a rod that can be moved up and down with a guide pin attached to the tip is placed in the electrode holder,
A lower electrode of a resistance welding machine in which the tip of the guide pin can be protruded and retracted from the hole of the electrode tip by moving the rod up and down,
A guide pin lower end receiving portion is provided at the tip of the rod, and a ball chuck mechanism is attached to the receiving portion.
A lower electrode of a resistance welding machine, wherein the guide pin is attached and detached by causing a ball of a chuck mechanism to protrude and retract in an annular groove formed at a lower end portion of the guide pin. Ball chuck mechanism
A ball slidably set in a ball holding hole formed in a radial direction on the peripheral wall surface of the receiving portion;
It is a cylinder that covers the peripheral wall surface and is freely slidable up and down, and is normally repelled on the front side of the electrode by a resilient member,
A tapered surface having an inner diameter gradually increasing toward the upper end opening is formed on the inner peripheral surface of the cylindrical body,
When the cylindrical body is positioned on the front side of the electrode, the portion with the small inner diameter of the tapered surface presses the ball toward the center portion, so that the ball tip engages with the annular groove provided at the lower end of the guide pin. When,
When the cylindrical body is moved to the rear side of the electrode against the impact, the ball is retracted until it comes into contact with a portion having a large inner diameter of the tapered surface, and the ball tip portion is disengaged from the annular groove portion. The lower electrode of the resistance welder according to claim 1, wherein the lower electrode has a structure capable of taking an aspect.   The lower electrode of a resistance welding machine according to claim 1 or 2, wherein a plurality of ball holding holes are formed at equal intervals in the radial direction of the peripheral wall surface.